A 14-year old Danbury High School student is the featured performer at tomorrow's Stanley L. Richter Association for the Arts concert.  Timothy Chen will be joined by Ava Turner in performing works by Beethoven, Bach, and others at Richter House at 3pm.  Chen has been studying the piano for eight years and has won recognition for his talent and dedication.  Ava Turner is a 17-year-old home-schooled senior.  Admission is free.